Contributors: Leon E. Pavlick and Laurel K. Anderton
Changes to published treatment in blue are based on examination of specimens. The addition of Bromus squarrosus var. villosus is based on Saarela (2008)

Plants perennial, annual, or biennial; usually cespitose, sometimes
rhizomatous. Culms 5190 cm. Sheaths closed to near the top, usually
pubescent; auricles usually absent; ligules membranous, to 6 mm, usually
erose or lacerate; blades generally
flat, rarely involute. Inflorescences
panicles, sometimes racemose, erect or nodding, open or dense, occasionally 1-sided;
branches usually ascending to
spreading, sometimes reflexed or drooping. Spikelets 570 mm, terete to laterally compressed, with 330 florets; disarticulation above the glumes, beneath
the florets. Glumes unequal, usually
shorter than the adjacent lemmas, always shorter than the spikelets, glabrous
or pubescent, usually acute, rarely mucronate; lower glumes 17(9)-veined; upper
glumes 39(11)-veined; lemmas 513-veined,
rounded to keeled, glabrous or pubescent, apices entire, emarginate, or
toothed, usually terminally or subterminally awned, sometimes with 3 awns or unawned; paleas usually shorter than the
lemmas, ciliate on the keels, adnate to the caryopses; anthers (2)3. x = 7. Name
from the Greek bromos, an ancient
name for oats, which was based on broma, food.

Bromus grows in temperate and cool regions, and is estimated to
include 100400 species, depending on differences in how the species are
interpreted. Of the 52 species in the Flora
region, 28 are native and 24 are introduced. The native perennial species
provide considerable forage for grazing animals, with some species being
cultivated for this purpose. The introduced species, all but three of which are
annuals, range from sporadic introductions to well-established members of the
regions flora. Many are weedy and occupy disturbed sites. Some are used for hay;
others have sharp, pointed florets and long, rough awns that can injure grazing
animals.

1.Lemmas unawned or with awns to 3.5 mm long; lemmas usually glabrous,
sometimes pubescent distally, veins prominent for most of their length........................................................................ 1.
B. catharticus

2.Lower panicle branches usually less than 10 cm long, with 15
spikelets variously distributed; culms less than 4 mm thick.

4.Upper glume about as long as the lowest lemma in each spikelet;
lemmas glabrous or pubescent distally or throughout, the marginal hairs, if
present, longer than those elsewhere...... 3.
B. arizonicus

4.Upper glume shorter than the lowest lemma in each spikelet; lemmas glabrous
or pubescent only on the margins or throughout, if throughout, the marginal
hairs similar in length to those elsewhere.

16.All or most upper glumes within a panicle 3-veined, sometimes some with
2 additional faint lateral veins; collars glabrous or hairy, hairs evenly
distributed over the surface, not in a dense line; lower sheaths glabrous or
hairy, not sericeous; ligules to 6 mm long.

23.Midrib of the culm leaves abruptly narrowed just below the collar;
auricles frequently present on the lower leaves; plants of western Texas................................................................................ 19.
B. anomalus

23.Midrib of the culm leaves not abruptly narrowed just below the collar;
auricles sometimes present; plants of various distribution, including Texas.

Bromus sect. Ceratochloa
is native to North and South America, and contains about 25 species. It is marked
by polyploid complexes; the major one in North America is the Bromus carinatus complex. This treatment
recognizes six species in the complex: B.
aleutensis,B. arizonicus, B. carinatus, B.
maritimus,
B. polyanthus, and B. sitchensis. The lowest chromosome number known for
members of this complex is 2n = 28,
found in B. carinatus; the highest is
2n = 84, found in B. arizonicus. The remaining species are
octoploids with 2n = 56, or
hexaploids with 2n = 42. One other
species in the section,B. catharticus, has been introduced from
South America and is also part of a polyploid complex.

There is morphological
intergradation among the species recognized here, and some evidence that these
intermediates are sometimes partially fertile (Harlan 1945a, 1945b; Stebbins
and Tobgy 1944; Stebbins 1947). Stebbins and Tobgy (1944) commented that
partial hybrid sterility between plants placed in different species on the
basis of their morphology supports the recognition of more than one species
among the octoploid members of the complex, but later Stebbins (1981) stated
that . . . all the North American octoploids . . . should be united into a
single species, in spite of the barriers of hybrid sterility that separate them.

Bromus catharticus var. catharticusis native to
South America. It has been widely introduced in the Flora region as a forage crop and is now established, particularly
in the southern half of the United States. It usually grows on disturbed soils.

Bromus catharticus var. elatus,
a native of South America, now grows in disturbed soils in central California.
It has also been reported from ballast dumps in Oregon; the specimens located
are actually var. catharticus.

Although published as
var. elata, the correct Latin
ending is var. elatus.

Bromus sitchensisgrows on exposed rock bluffs and
cliffs, in meadows, often in the partial shade of forests along the ocean edge,
and on road verges and other disturbed sites. Its range extends from the
Aleutian Islands and Alaska panhandle through British Columbia to southern
California.

Bromus sitchensis resembles B.
aleutensis, the two sometimes being treated as conspecific varieties.

Bromus arizonicusgrows in dry, open areas and
disturbed ground of the southwest, usually below 2000 m. Its range extends from
California and southern Nevada into Arizona, New Mexico, Colorado, and northern
Mexico.

Stebbins et al. (1944)
demonstrated that, like Bromus carinatus, B. arizonicus
obtained three of its genomes from B. catharticusor a close relative, but the remaining three
genomes are not homologous with those in B. carinatus, probably being
derived from a species in a section other than Ceratochloa. The small
anthers of B. arizonicus strongly
suggest that most seed is produced by selfing.

Bromus aleutensisgrows in sand, gravel, and disturbed
soil along the Pacific coast, from the Aleutian Islands of Alaska to western
Washington, and on some lake shores of central British Columbia. It has also
been found further east in Canada and in northern Idaho, always in disturbed
sites, such as road edges.

Hultιn (1968) suggested
that Bromus aleutensis might represent a modified version of B.
sitchensis,
in which reproduction occurs at a relatively early developmental state in
response to the climatic conditions of the Aleutian Islands. C.L. Hitchcock
(1969) reported that B. aleutensis is predominantly self-fertilizing, and
B. sitchensisis
predominantly outcrossing. Anther lengths close to 4.2 mm suggest that at least
some plants of B. aleutensis are
outcrossing.

Bromus carinatus is native from British Columbia to Saskatchewan and
south to Mexico. It has been introduced to various more eastern locations, and
to the southern Yukon Territory. The two varieties recognized here are
sometimes recognized as species.

Bromus carinatus var. carinatus
is primarily coastal and grows in shrublands, grasslands, meadows, and openings
in chaparral and oak and yellow pine woodlands. It ranges from southern British
Columbia through Washington, Oregon, and California to Baja California, Mexico,
and extends eastward through Arizona to New Mexico.

30 Aug 2007: Changes to description based on UTC 247610, collected by John Anderson.

Bromus carinatus var. carinatus
intergrades with var. marginatus, which tends to grow at
higher elevations and extends further inland.

Bromus carinatus var. marginatus is primarily an
inland species and grows on open slopes, grass balds, shrublands, meadows,
and open forests, in montane and subalpine zones. It grows from British
Columbia to Saskatchewan, south throughout the western United States, and also
extends into northern Mexico. Its elevational range is 3502200 m in the
northern part of its distribution, and 15003300 m in the south.

Bromus carinatus var. marginatus is variable, and
intergrades with B. carinatus var. carinatusto the west, B. aleutensisto the north, and B.polyanthusto the southeast. As treated here, B. carinatus var. marginatus includes B.
luzonensis J. Presl,
which has been recognized mainly on the basis of its canescent sheaths and
blades; this trait seems highly variable and may be environmentally determined.
Although the name Bromus carinatus var.
marginatus was attributed to
Hitchcock by Scoggan, there is no evidence that either A.S. or C.L. Hitchcock
actually made the combination.

Bromus polyanthus
grows on open slopes and in meadows. It is found primarily in the central Rocky
Mountains, but the limits of its range include British Columbia in the north,
California in the west, and Arizona, New Mexico, and western Texas in the south.
It is sometimes treated as var. polyanthuswith an erect, contracted panicle and awns 46
mm long; and as var. paniculatuswith an open, nodding panicle and awns up to 8
mm long. Because the variation in both characters is continuous, the varieties
are not recognized here.

Bromus inermis is native to Eurasia, and is now found in disturbed
sites from Alaska and most of Canada south through most of the United States,
except the southeast. It has also been used for rehabilitation, and is planted
extensively for forage in pastures and rangelands from Texas to Alaska and the Yukon
Territory.

Bromus inermis is similar to B.
pumpellianus,
differing mainly in having glabrous lemmas, nodes, and leaf blades, but a lack
of pubescence is not a consistently reliable distinguishing character. Bromus inermis also resembles a recently
introduced species, B.riparius, from which it differs primarily
in its shorter or nonexistent awns.

Bromus riparius is an Asian species that was introduced to the
United States in the late 1950s for cultivation as a pasture grass. Various
cultivars are now grown, mainly in Canada and the northwestern United States. The
description given here is derived in part from cultivated specimens. North
American plants have sometimes been referred to incorrectly as Bromus biebersteinii Roem. & Schult.(Vogel et al. 1996). Bromus riparius differs from that species in having acute lemma
apices and, usually, more pubscent leaf blades, sheaths, and lemmas.

The existence of Bromus riparius in the Flora region was not realized until
shortly before this treatment was submitted for publication, making it impossible
to fully investigate its similarities to B.
inermisand B.
pumpellianus,
particularly subsp. dicksonii. It appears to differ from both
species in having shorter culms on average, longer awns than B. inermis, and shorter rhizomes than B. pumpellianus subsp. pumpellianus.

The range of Bromus pumpellianus extends from Asia to
North America, where it includes Alaska, the western half of Canada, the
western United States as far south as New Mexico, and a few other locations
eastward. It has been treated as a subspecies of B. inermis.
It differs from that species primarily in its tendency to have pubescent
lemmas, nodes, and leaf blades.

Two subspecies that differ
in morphology and distribution are described below. Both strongly resemble the
recently introduced B. riparius, differing in the case of B. pumpellianus subsp. pumpellianusin having longer rhizomes, or, in the case of B. pumpellianus subsp. dicksonii, in having a more restricted
distribution. It is possible that the description and distribution of B. pumpellianus may be based in part on
misidentification of B. riparius, as
many taxonomists may have been unaware of the introduction of the latter
species to North America.

Bromus pumpellianus subsp. dicksonii
grows in shallow, rocky soils of river banks and bluffs in the Yukon River
drainage of Alaska. Apart from the more restricted distribution, it is not
clear how this subspecies differs from the introduced B. riparius.

Bromus latiglumis grows in shaded or open woods, along stream banks,
and on alluvial plains and slopes. Its range is mainly in the north-central and
northeastern United States and adjacent Canadian provinces. Specimens with
decumbent, weak, sprawling culms, densely hairy sheaths, and heavy panicles can
be called Bromus latiglumis forma incanus (Shear) Fernald.

Bromus pseudolaevipes grows in dry, shaded or semishaded sites in
the chaparral, coastal sage scrub, and woodland-savannah zones, from near sea
level to about 900 m, in central and southern California.

Bromusorcuttianus grows
on dry hillsides and rocky slopes, and in open pine woods and meadows in the
mountains, from 5003500 m. It is found in the western United States, including
Washington, Oregon, California, Nevada, and Arizona.

Bromus anomalus grows on rocky slopes in western Texas and adjacent
Mexico. Many records of this species in the Flora
region are here treated as B. porteri, a closely related species
that has sometimes been included in B.
anomalus. The two differ mainly in B.
anomalus having culm leaves with midribs that are narrowed just below the
collar, as well as auricles.

Bromus porteri grows in montane meadows, grassy slopes, mesic
steppes, forest edges, and open forest habitats, at 5003500 m. It is found
from British Columbia to Manitoba, and south to California and western Texas. It
is closely related to B. anomalus, and has often been included in that species. It
differs chiefly in its lack of auricles, and in having culm leaves with midribs
that are not narrowed just below the collar.

Bromus nottowayanus is native to the east-central and eastern United
States, from Iowa to New York, south to Oklahoma, northern Alabama, and
Virginia. It grows in damp, shaded woods, often in ravines and along streams.

Bromus vulgaris grows in shaded or partially shaded, often damp,
coniferous forests along the coast, and inland in montane pine, spruce, fir,
and aspen forests, from sea level to about 2000 m. Its range extrends from
coastal British Columbia eastward to southwestern Alberta and southward to
central California, northern Utah, and western Wyoming.

Varieties have been
described within Bromus vulgaris;
because their variation is overlapping, none are recognized here.

Bromus erectus is native to Europe. In the Flora region, it grows on disturbed soils, often over limestone. It
is established in the eastern United States and Canada, and has been reported
from other locations where it has not persisted.

Bromus pubescens grows in shaded, moist, often upland deciduous
woods. Its range is centered in the eastern half of the United States, and
extends northward to southern Manitoba, Ontario, and Quebec, westward in
scattered locations to Arizona, and southward to eastern Texas and western Florida.

Bromus ramosus is native to Asia, Europe, and northern Africa. It
is included here based on Pavlicks (1995) statement that it is found
sporadically in the southern and eastern United States; specimens to
substantiate his statement have not been located.

Bromus ciliatus grows in damp meadows, thickets, woods, and stream
banks across almost all of northern North America except the high arctic,
extending further south mainly in the western United States. Some taxonomists
have named plants with different degrees of sheath pubescence as different
forms. Because the variation is continuous, such differences are not formally
recognized in this treatment.

Bromus richardsonii grows in meadows and open woods in the upper
montane and subalpine zones, at about 20004000 m in the southern Rocky
Mountains, and at lower elevations northwards. Its range extends from southern
Alaska to southern California and northern Baja California, Mexico; it is found
as far east as Saskatchewan, South Dakota, and western Texas. Specimens with
pubsecent nodes and glumes are apparently confined to the southwestern United
States.

Bromus diandrus is native to southern and western Europe. It is now
established in North America, where it grows in disturbed ground, waste places,
fields, sand dunes, and limestone areas. It occurs from southwestern British
Columbia to Baja California, Mexico, and eastward to Montana, Colorado, Texas,
and scattered locations in the eastern United States. The common name ripgut
grass suggests possible damage to animals if they consume the sharp,
long-awned florets of this species.

Bromus diandrus, as treated here, includes B. rigidus Roth. Sales (1993) reduced these
two taxa to varietal rank, and pointed out that the differences between them
are subtle enough that identification of many specimens beyond B. diandrussensu lato is often impossible.

Bromus sterilis is native to Europe, growing from Sweden southward.
It now grows in North America in road verges, fields, waste places, and
overgrazed rangeland. It is widespread in western and eastern North America, but
is mostly absent from the Great Plains and the southeastern states.

Bromus tectorum
is a European species that is well established in the Flora region and other parts of the world. It grows in disturbed
sites, such as overgrazed rangelands, fields, sand dunes, road verges, and
waste places. It is highly competitive and dominates rapidly after fire,
especially in sagebrush areas. The resulting dense, fine fuels permanently
shorten the fire-return interval, further hindering reestablishment of native
species. It now dominates large areas of the sagebrush ecosystem of the western
Flora region. See Schachnet et al. 2008 discuss the population genetics of this species in the midcontinental United States and cite earlier papers on a similar topic for other parts of the country.

In the southwestern
United States, Bromus tectorum is
considered a good source of spring feed for cattle, at least until the awns
mature. Specimens with glabrous spikelets have been called Bromus tectorumforma nudus (Klett & Richt.) H. St. John. They occur throughout the
range of the species, and are not known to have any other distinguishing
characteristics. For this reason, they are not given formal recognition in this
treatment.

Bromus madritensis is native to southern and western Europe. It is
now established in North America, and grows in disturbed soil, waste places,
banks, and road verges in southern Oregon, California, and Arizona.

Bromus rubens is native to southern and southwestern Europe. It now
grows in North America in disturbed ground, waste places, fields, and rocky
slopes, from southern Washington to southern California, eastward to Idaho, New
Mexico, and western Texas. It was found in Massachusetts before 1900 in wool
waste used on a crop field; it is not established there.The record from New York represents a rare
introduction.

Bromus briziformis grows in waste
places, road verges, and overgrazed areas. It is native to southwest Asia and
Europe, and is adventive in the Flora
region, occurring from southern British Columbia as far south as New Mexico, and
in scattered locations eastward. The unique shape of its spikelets has led to
its use in dried flower arrangements and as a garden ornamental. The common
name may refer to the similarity of the spikelets to a rattlesnakes tail.

Bromus secalinus is native to Europe. It
is widespread in the Flora region,
where it grows in fields, on waste ground, and along roadsides. Specimens with
pubescent spikelets may be called B.
secalinus var. velutinus
(Schrad.) W.D.J. Koch.

Bromus commutatus grows in fields, waste
places, and road verges. It is native to Europe and the Baltic region; in the Flora region, it is found mainly in the
United States and southern Canada. It resembles B. racemosus. Hildemar Scholz (pers.
comm.) recognizes three subspecies of B.
commutatus in Europe; no attempt has been made to determine which subspecies
are present in the Flora region.

Bromus lepidus grows in fields and waste
places. It is native to Europe, and is reported from New York and Massachusetts;
it probably also occurs elsewhere in the Flora
region.

Specimens
of Bromus hordeaceus subsp. pseudothomineioften approach B. lepidus in lemma characteristics (e.g., length, smoothness, and
margin angle), so that either may be misinterpreted. Characteristics helpful in
distinguishing B. lepidus are the
wide apical notch on the lemmas, and the length of the caryopses relative to
the paleas.

Bromus
hordeaceus is native to southern Europe and northern Africa. It is weedy,
growing in disturbed areas such as roadsides, fields, sandy beaches, and waste
places, and can be found in many locations in the Flora region, with the exception of the central Canadian provinces
and most of the southeastern United States. Its origin is obscure. Ainouche et al. (1999) reviewed various
suggestions, and concluded that at least one of its diploid ancestors may have
been an extinct or undiscovered species related to B. caroli-henrici, a
diploid species.

The
four subspecies are usually morphologically distinct. Ainouche et al.
(1999), however, found no evidence of genetic differentiation among them.

Culms 1525(60) cm. Panicles to 10 cm, usually with more
than 1 spikelet. Lemmas (7)811 mm,
pubescent, margins rounded; awns
less than 0.1 mm wide at the base, often divaricate or recurved at maturity. Caryopses shorter than the paleas.

Bromus hordeaceus subsp. molliformis grows in California and
other scattered locations, including Idaho, New Mexico, and southern Michigan.

Bromus hordeaceus subsp. pseudothominei
(P.M. Sm.) H. Scholz

Culms (3)1070 cm. Panicles to 10 cm, usually with more than 1 spikelet. Lemmas 6.58(9) mm, usually glabrous,
margins often abruptly angled; awns
straight, erect. Caryopses usually
as long as the paleas.

Bromus hordeaceus subsp. pseudothominei grows sporadically
throughout the range of the species in the Flora
region. Hitchcock (1951) included B.
hordeaceus subsp. pseudothominei in
B. racemosus.

Bromus hordeaceus subsp. thominei grows along the Pacific coast
of Canada, from the Queen Charlotte Islands to Vancouver Island, as well as at inland
locations in British Columbia; it has also been recorded from California, Massachusetts,
and Rhode Island.

Bromus racemosus grows in fields, waste
places, and road verges. It is native to western Europe and the Baltic region,
and occurs throughout much of southern Canada and the United States. It is similar
to B. commutatus. Hitchcock (1951) included B. hordeaceus subsp. pseudothomineiin B.
racemosus.

Bromus caroli-henrici is native to Mediterranean
Europe. In the Flora region, it grows
in open, disturbed areas in north-central California. It has been misidentified
as B. alopecuros Poir., but differs mainly in having
single spikelets at the nodes versus 23, and in its acuminate versus broadly
triangular lemma teeth.

Bromus lanceolatus grows in waste places,
and is also cultivated as an ornamental. It has been introduced to the Flora region from southern Europe, and
is reported from scattered sites, e.g., Yonkers, New York (wool waste); College
Station, Texas; and Pima County, Arizona.

Bromus arenarius grows in dry, often
sandy slopes, fields, and waste places. Native to Australia, it is now widely
scattered throughout California, and is also recorded from Oregon, eastern
Nevada, Arizona, New Mexico, Texas, and Pennsylvania.

Bromus japonicus grows in fields, waste
places, and road verges. It is native to central and southeastern Europe and
Asia, and is distributed throughout much of the United States and southern
Canada, with one record from the Yukon Territory.

Bromus squarrosus grows in overgrazed pastures,
fields, waste places, and road verges. Native to central Russia and southern Europe,
it can be found mainly in southern Canada and the northern half of the United
States. Saarela (2008) reported the presence of the two varieties described below in in his treatment of Bromus for British Columbia. The description in FNA 24 applied only to var. squarrosa. The description given here has been amended to include both varieties.

At present, known in North America only from specimens cited by Saarela (2008), all of which came from southern British Columbia. Examination of specimens of Bromus squarrosus from other areas may show it to be more widespread in North America.